This invention relates to the field of living test subject signal interfacing and to the collection of vertebrate test subject originating stress-influenced data signals.
Spatial disorientation, which is also known as attitude perception error, is known to present a significant threat to an aircraft pilot or other flight vehicle crewmember. Indeed, many of the aircraft fatalities, injuries, and property loss incidents occurring since the Wright brothers era have been attributed to erroneous perceptions of aircraft attitude and the resulting pilot action. In the early days of flying, before the array of flight instruments now routinely used was available, it was indeed necessary for a pilot to fly an aircraft with considerable attention to the forces incurred by his body--i.e., to fly literally by the "seat of his pants" in order to maintain a coordinated pattern of flight.
These early flying procedures relied heavily and sometimes perilously on what is now termed "vestibular perception", a term which describes perception based on the central cavity of the bony labyrinth of the ear and parts of the membranous labyrinth that it contains. A related concept known as "Proprioceptive perception" was also used instinctively by these early flyers and continues to be important even in the present invention. Proprioceptive perception refers to other body sensing capabilities such as pressure on the torso or portions of the peripheral limbs.
It is now well understood that spatial disorientation results from an error between a test subject's perceived orientation and his/her actual orientation. A discussion of this concept is to be found in the technical article "Erroneous Perception of Vertical Motion by Humans Seated in the Upright Position", by Jones Malcolm, (Acta Oto-Laryngologica, May 1977). It is also well understood that a test subject may be unaware that he/she is a victim of spatial disorientation, especially for transient periods that are incompatible with the duties imposed on a modern aircraft pilot.
A classic example of spatial disorientation and its danger is known to naval aviation pilots from the carrier-launched aircraft sequence. During aircraft rest or taxi maneuvers on a carrier flight deck, the pilot of such an aircraft perceives the gravity vector to be in its correct and straight down location. This perception is drastically influenced, however, by the forces of engine thrust and catapult launch acceleration. During a full throttle, catapult-assisted takeoff, such a pilot experiences a sharp backward rotation of the apparent direction of the gravity vector--as a result of the summation of the true gravity vector with the horizontally directed force vectors from engine thrust and catapult force. Because of this backward rotation, an inexperienced person tends to apply attitude correction to the aircraft in order to rotate the force summation vector back to the normal position of gravity. This correction is accomplished by rotating the nose of the aircraft downward just after take-off. In this instance, an erroneous perception and its first blush nose-down correction has obvious life-threatening potential for a pilot who has just left the deck of an aircraft carrier and is already in a marginal altitude and speed condition of flight.
Ambient vision is the primary and usually reliable mechanism by which an aircraft crewmember can overcome an incident of spatial disorientation and achieve correct orientation of an aircraft. Pilots are, however, often deprived of this ambient vision input while in flight--deprived by such conditions as clouds, weather, darkness, pilot distractions, and even formation flying; such effects are described in the published article "Pilot Disorientation and Use of a Peripheral Vision Display", by Richard Malcolm (Aviation, Space and Environmental Medicine, March 1984).
During periods of deprived ambient vision, a pilot notwithstanding the availability of usually reliable flight instruments, can be strongly influenced by vestibular or middle ear perceptions of his or her orientation. As is well known in the aviation art, however, these vestibular system perceptions are, as in the case of the Navy aircraft carrier pilot, subject to acceleration illusions. Moreover these accelerations are not limited to one axis or direction of action, but may have multiple axis components.
In view of the demands placed upon the pilot of a modern aircraft, particularly by a tactical aircraft, demands including the tolerance of large and relatively long-term g-forces from a range of differing directions, there is an immediate need in the aerospace community to understand the effects of multi-axis maneuvering on vestibular perception in the absence of ambient vision. This need has been recognized in the technical community, as is evidenced by such news publications as "F-117 Crash Reports Cite Pilot Fatigue, Disorientation" by William B. Scott (Aviation Week & Space Technology, May 1989), and "Spatial Disorientation and Loss of Attitude Awareness: Impact on the USAF" by Britton L. Marlowe, (58th Annual Scientific Meeting of the Aerospace Medical Association, May 1987).
The information obtained from an improved understanding of multi-axis maneuvering effects on vestibular perception can be used to improve the design of aircraft and their instrumentation systems, and to improve the instruction of aircraft pilots, especially by way of acquainting experienced instructor pilots with newly-acquired factual information. Studies in this field may be made in aircraft, but are, however, more cost effectively and conveniently accomplished in ground-based dynamic effect simulators, g-force simulators or centrifuges, in which a test subject can be exposed to a controlled variety of conditions such as off-axis positioning, darkness, presence of clutter information, a regimen of distracting duties, and variations of ambient conditions--all under the greatest possible degree of monitoring, safety, and repeatability.
Several arrangements have, in fact, been used to identify the perceived attitude of a test subject while exposed to such conditions. Most of these arrangements have been based on a single pivot point transducer arrangement that is operated by the test subject. Included in these previously used devices is the horizontal bar which is rotated to indicate perceived roll angle as is described by M.J. Correia et al in the publication "On Predictive Equations for Subjective Judgments of Vertical and Horizon in a Force Field" (Acta Octo-Laryngologica, 1968). In addition, Gillingham et al in the paper "Quantification of the Somato Gravic Illusion in the Vertifuge", (58th Annual Scientific Meeting of the Aerospace Medical Association, May 1987), have worked with a "down pointer" which is pivoted at the top of a cockpit or test chamber and is used by the test subject to indicate his/her perception of the down direction.
These previous attitude communicating arrangements have, however, overlooked a useful and inherent tendency of people, especially aircraft pilots, to talk with their hands. This well-known tendency usually includes use of the palm of the hand to indicate the downward direction or lower surface of an aircraft. These previously employed attitude communicating transducers have also been limited in effectiveness by the tendency of the down pointer to act as a pendulum and to thereby provide a reference frame or biasing information to a test subject
The down pointer is also limited by a more subtle and human experience related concept in that people are accustomed to orienting themselves with respect to a horizon rather than a vertical object. Since pilots are also accustomed to a horizontal attitude indication, a down pointer arrangement may well introduce error into any obtained measurement simply because people are poorer judges of "down" than of "level". The herein-described perceived attitude transducer provides an improvement over previous communication arrangements and also provides a tool for testing the significance of possible perceived attitude biasing factors. The presently described perceived attitude transducer also makes use of the natural inclination of pilots to talk with their hands and to describe their orientation in space by movement of a prone hand into a selected orientation with respect to their torso.
The patent art reveals a number of inventions that are concerned with the straight and level condition for a variety of objects. Included in this art is the U.S. Pat. No. 3,478,569 of H.H. Aichinger, which is concerned with an apparatus usable in the rigging of airplane control surfaces, that is, the alignment of control surfaces to the neutral or straight and level flight condition at initial manufacture and assembly of the aircraft.
This patent art also includes the U.S. Pat. No. 3,561,123, of C.G. Bowman et al, which is concerned with a hand level apparatus having a vertically disposed and horizontally elongated closed liquid reservoir. Also included in this patent art is the U.S. Pat. No. 4,189,726 of Frank Rosa et al, which provides a level orientation indication for a portable power hand tool such as an electric drill.
Additionally included in this patent art is the U.S. Pat. No. 4,484,191 of G.S. Vavra, in which tactile or feeling-sensed signals indicating the execution of an uncoordinated turn condition by an aircraft are provided. Also included in this patent art is the U.S. Pat. No. 4,713,651 of Myer Morag in which tactile or feeling senses are used to display information in an information saturated environment such as a modern aircraft cockpit.
While each of these prior patents bears some distal relationship with the present invention, none of these patents nor their combination provide a g-force disregarding reliable communication path from a human or other test subject to, for example, a data processing system.